1. Field of the Invention
The present invention relates to a structure for storing an ink jet head for effecting recording by discharging recording liquid from a discharge port.
2. Related Background Art
Among conventional recording systems, since an ink jet recording system for effecting recording on a recording medium by discharging ink from a discharge port has less noise and can achieve a high speed recording operation with high density, such a system has widely been used recently.
A general recording apparatus having such a system includes an ink jet head for discharging the ink to form an image on the recording medium, and a conveying device for conveying the recording medium.
As the ink jet heads, there are an ink jet head in which an electrothermal converting element such as a piezo-element is provided in a nozzle communicated with a discharge port to discharge an ink droplet from the discharge port, an ink jet head in which an electrothermal converting element such as a heat generating resistance body and an ink jet head in which an electromagnetic wave (such as electric wave or laser)/mechanical converting element or an electromagnetic wave/thermal converting element is used. Among them, in an ink jet recording apparatus of type in which the ink droplet is discharged by utilizing thermal energy, since nozzles can be arranged with high density, recording having high resolving power can be achieved.
Particularly, in an ink jet head using the electrothermal converting element as a thermal energy generating element, compactness can easily be achieved in comparison with the ink jet head using an electrical/mechanical converting element, and, further, high density arrangement can easily be achieved with low cost by adequately utilizing merits of IC techniques and micro-working techniques, progress and reliability of which have been enhanced considerably in a recent semiconductor manufacturing field. A wiring substrate having base material of glass/epoxy for transmitting an electrical signal sent from a main body of the recording apparatus to a heater board provided in a converting portion of the converting element is adhered to the ink jet head. The heater board and the wiring substrate are interconnected by wire bonding. A contact pad contacted with and electrically connected to a flexible wiring substrate of the main body of the recording apparatus is provided on an upper surface of the wiring substrate.
In general ink jet heads, an ink amount required for the recording is stably supplied from an ink tank containing ink to nozzles. Further, in order to prevent leakage of ink through the discharge port, and more particularly, in order to maintain ink meniscus in the discharge port not to be broken, ink supplying pressure from the ink tank to the nozzles is adjusted to be negative pressure. As methods for adjusting the ink supplying pressure to be negative pressure, there are a method utilizing difference in water head from an ink introduction port of the ink tank directly containing the ink to the discharge port and method in which an ink absorbing body as a negative pressure generating member is disposed within the ink tank.
As methods for supplying the ink to the nozzles of the ink jet head, there are a method in which the ink is supplied to the nozzles by integrally or separately mounting the ink tank to the ink jet head on the carriage and a so-called tube supplying method in which the ink is supplied to the nozzles by connecting the ink jet head to the ink tank out of the carriage through a tube. In an ink jet printer consuming a large amount of ink, the ink tank must have a large capacity. In this case, if the ink tank having the large capacity is mounted on the carriage, since the ink jet printer itself becomes bulky, in such a printer, the tube supplying method is adopted.
In the ink jet head of tube supplying type, a buffer portion such as an ink reservoir, a filter or the like for storing the ink auxiliarily is provided between the ink tank and the head to prevent poor discharging and leakage of ink due to abrupt pressure change. Further, nozzles, ink storing space and ink introduction port which constitute an ink droplet discharging portion are also provided.
In such an ink jet head, if the nozzles are dried upon usage, when the ink is supplied into the nozzles, since ink wetting abilities of inner surfaces of the nozzles is changed, poor discharging may occur due to uneven wetting ability. To avoid this, when the head is transported, by filling the nozzles with ink not including color material (transparent ink not including color material), the head (interior of the nozzles) is maintained to a wetting condition. If the color material is included in the ink, when moisture which is main component of the ink is vaporized, the color material solved in the moisture is educed to clog the nozzles. The reason why the color material is not included in the ink not including the color material is that such clogging is prevented.
By the way, some ink jet heads of tube supplying type mounted on the carriage are designed so that air is housed in the ink storing portion containing the ink to be supplied to the nozzles. However, when the ink jet head of the type in which the air is housed in the ink storing portion is reserved, if inner pressure of the head is increased due to environmental change in a reserving step from the manufacture of the head to forwarding of the head or environmental change in a transporting step from the forwarding of the head to the transferring of the head to the user, the ink not including the color material may leak from the discharge ports of the nozzles or the ink introduction port.
Further, such leakage of the ink not including the color material may be further noticeable in dependence upon the posture of the head during the transportation.
In order to prevent the ink from leaking from the nozzles, it is considered that a tape or rubber sheet is directly adhered to the face surface to seal the nozzles. However, when the air is housed as mentioned above, pressure increase due to expansion of air becomes great, and, thus, in order to prevent the ink leakage, the tape or rubber sheet must be urged against the face surface with a considerably strong force. However, if the tape or rubber sheet is urged against the face surface with the strong force, the nozzles may be deformed. Further, foreign matters such as diry may be pinched between the tape or rubber sheet and the face surface to clog the nozzles, or adhesive of the tape may transfer to the face surface to change the ink wetting ability or damage the face surface.